Engine crankcase ventilation

ABSTRACT

In a preferred embodiment, a crankcase ventilation system utilizes the combination of a fixed orifice and a pressure actuated regulating valve downstream of the orifice to control vapor flow from the engine crankcase into its induction system. The arrangement provides controlled vacuum in the engine crankcase during normal operation but permits the development of pressure during abnormal conditions of excessive blowby or the like so as to permit actuation of a crankcase pressure actuated shutdown device associated with the engine.

United States Patent 1191 Ephraim, Jr. et a1.

1451 Aug. 28, 1973 I PREssuRE DETECTOR \ENGINE CRANKCASE 15 ENGINECRANKCASE VENTILATION 2,493,617 1/1950 Chubbuck 123/119 1; Inventors: Mmp I J Evergreen Paxk; 3,246,641 4/1966 Goehrmg 123/198 R L dvlk F. KoelLaG P k,

g of m range a Primary Examiner-A1 Lawrence Sm1th 1919 Earnin T9"! 1Alslgmei Geller" cmpol'ifloll, Attorney-J. L. Carpenter and Robert J.Outland Detroit, Mich. 1

[22] Filed: Nov. 2, 1971 [57] ABSTRACT [21] Appl. No.1 194,930 In apreferred embodiment, a crankcase ventilation system utilizes thecombination of a fixed orifice and a [52] us Cl. 123/41 86 123/119 8123/198 D pressure actuated'regulating valve downstream of the 5! l[MIC]. F02 9/02 orifice to control vapor flow from the engine crankcase[58] Field B 41 86 into its induction system. The arrangement providescontrolled vacuum in the engine crankcase during nor- 56] adenine Cmdmal operation but permits the development of pressure during abnormalconditions of excessive blowby or the UNITED STATES PATENTS like so asto permit actuation of a crankcase pressure 3,418,986 12/1968Scherenberg 123/119 B actuated h td w dgvice associated with the engine.3,225,752 12/1965 Robinson 123/119 B 3,263,660 8/1966 Hyde 123/119 R 4Claims, 2 Drawing Figures ORIFICE /Z I 1 1 \\\1 1\\\ ENGiNE/ OILREGULATING VALVE AIR INLET SEPARATOR PATENTEB M28 I78 OI L SEPARATOR-\:\PRESSURE DETECTOR ENGINE CRAN KCASE ENGINE AIR INLET REGULATINGVALVE 1 ENGINE CRANKCASE VENTILATION BACKGROUND OF THE INVENTION Thisinvention relates to crankcase ventilation systems for internalcombustion engines and, more particularly, to a crankcase ventilationsystem having the capability of maintaining a predetermined vacuum inthe engine crankcase under normal operating conditions, includingvarying inlet pressures while permitting the development of pressure inthe crankcase under abnormal engine conditions of high blowby or thelike.

In the operation of internal combustion engines and, specifically, largediesel engines used, for example, as power plants for diesel electriclocomotives and the like, it is desirable to maintain a small vacuum inthe crankcase under normal operating conditions. This has the advantageof reducing the amount of vapors maintained in the crankcase so that thepossibility of a crankcase explosion is minimized. In addition, itprovides a pressure difi'erential which acts at the various seals andother openings in the crankcase to reduce the possibility of oilescaping from the interior of the engine. There are, however, abnormaloperating circumstances for such engines which may result in excessiveamounts of blowby escaping into the crankcase and indicate the possibleor potential failure of certain engine parts. Continued operation undersuch conditions may cause serious engine damage and might lead to acrankcase explosion. Under such conditions, it is desired that theexcess flow of blowby into the crankcase will create a positive pressurethat will be detected by a crankcaseconnected pressure detector that isprovided to actuate an engine shutdown mechanism.

To maintain the desired crankcase vacuum, it has been known to providemeans to exhaust the crankcase vapors, including the blowby gases whichescape past the piston rings into the crankcase, through suitableconduit means into either the engine inlet or exhaust systems or, insome cases, to a separate exhaust device.

A typical system for recirculation of the crankcase gases into theengine inlet which is used on certain twocycle diesel engines includesan engine-mounted oil separator that communicates with the crankcase anda conduit connecting the oil separator with the engine combustion airinlet, at a point between the air filtration means and the charging airblower. A similar sys tem is shown, for example, in U.S. Pat. No.2,688,316 Brill. In such systems it is known to include a restrictiveorifice in the conduit to prevent an excessive flow of vapors throughthe system with the resultant carryover of oil from the oil separator.The orifice limits normal flow and provides for the development ofpositive pressure in the crankcase under abnormal conditions of highblowby. A pressure actuated protective device may be provided to actuateengine stopping means in response to the crankcase pressure, thuspreventing continued abnormal operation of the engine. An example ofsuch a protective device is shown in US. Pat. No. 3,246,641 Goehring.

Generally, the application of fixed orifices in the above-indicatedmanner has been limited to systems where the variation in inletdepression (negative pressure or vacuum) upstream of the blower isrelatively small. Where significant variations in inlet depressionexist, as in engines having the charging air supplied by a turbocharger,the above-described system is not especially suitable due to theexcessive variations in flow through the system which would beencountered under normal operating conditions. A number of crankcaseventilation systems are knwon in the prior art which provide for themaintenance of a suitable vacuum in the engine crankcase under thecontrol of a regulating valve. See, for example, US. Pat. Nos. 3,263,660Hyde and 3,380,441 Lewis. While such systems might be suitable for thecontrol of crankcase ventilation flow in large locomotive engines andthe like under their normal operating conditions, this would not be trueunder the abnormal conditions caused by excessive blowby indicative ofan engine malfunction and the possible occurrence of a crankcaseexplosion. Under such conditions, the regulating valves of the prior artsystems would respond to the increased crankcase pressure by openingcompletely. This action would permit the flow through the ventilationconduit to become excessive and deter the buildup of pressure in thecrankcase which is necessary to actuate the crankcase pressure detectorof the protective device and shut down the engine so as to prevent orminimize damage due to the abnormal conditions.

SUMMARY OF THE INVENTION The present invention provides a crankcaseventilation system which meets the requirements of large 10- comotiveengines and the like where it is desired to ventilate the crankcase intothe engine induction systern upstream of the charging air blower orturbocharger. The system is particularly adapted for conditions where asignificant variation in inlet depressions exists and it is desired tomaintain a suitable vacuum in the crankcase under normal operatingconditions but to permit the buildup of a crankcase pressure to actuatethe engine shutdown mechanism under conditions of abnormally high engineblowby or other similar indication of actual or potential enginefailure.

In essence, the system of the present invention involves the combinationof both fixed restriction means and a regulating valve in series in thecrankcase ventilation conduit with the fixed restriction locatedupstream of the regulating valve. Preferably, an orifice plate is usedas the fixed restriction and the regulating valve is arranged tonormally maintain a relatively constant vacuum in the space between theorifice plate and regulating valve. To provide flexibility of the systemfor application to various engine sizes and types, provision may be madefor the alternative use of various sizes of fixed orifices.Additionally, the regulating valve may be made adjustable to permitvarying the controlled pressure upstream thereof. The combination of thepresent invention provides for maintenance of crankcase vacuum in adesired range under normal engine operating conditions as controlledprimarily by movement of the regulating valve while permitting a buildupof pressure in the crankcase to actuate the engine protector underconditions of excessive blowby or a crankcase explosion.

These and other advantages of the present invention will be more clearlyunderstood from the following description of a preferred embodimenttaken together with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a side view of an internal combustion engine having acrankcase ventilation system according to the invention; and

FIG. 2 is a diagrammatic illustration of the crankcase ventilationsystem as applied to the engine of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing, numeralgenerally indicates an internal combustion engine which may be of anysuitable type, but in the present instance is shown as a large two-cyclediesel engine of a type commonly used to power diesel locomotives andfor other purposes. Engine 10 includes a crankcase 12 which in knownmanner provides an enclosure for the engine cylinders and operatingcomponents. Within the crankcase, blowby gases from the engine cylindersmix with oil vapors and other gases to form a mixture of crankcasevapors which it is desirable to draw from the crankcase.

Mounted on the engine crankcase is a turbocharger 14 which is driven bythe engine exhaust supplemented of the type shown in U. S. Pat. No.3,246,641 Goehrfrom the crankcase vapors. If desired, the oil separator26 may be spacedly mounted from the crankcase and connected thereto by aconduit. Oil separator 26 is connected with the turbine inlet 16 throughsuitable conduit means 28 that also communicate, through the oilseparator, with the engine crankcase 12. A fixed orifice plate 30 ismounted within conduit 28 downstream of the oil separator to provide aresistance to excessive fluid flow through the system. A suitableregulating valve 32 is also mounted within the conduit 28 intermediateorifice plate 30 and the turbine inlet.

Regulating valve 32 may be of any suitable type which is adapted to beresponsive to pressure upstream of the valve so as to control fluid flowas a function of such pressure. The valve is arranged so that duringengine operation it controls the flow of fluids through the ventilationconduit to provide during normal operation a predetermined maximumvacuum in the conduit 28 between the orifice plate and the regulatingvalve. One type of valve which might be usable for this purpose is shownin the previously mentioned U. S. Pat. No. 3,263,660 Hyde, although anyother suitable valve arrangement may be utilized.

In a specific example, the engine involved is such that vacuum in theturbocharger air inlet may vary between almost zero to 50 inches ofwater under various operating conditions. The valve 32 is arranged tocontrol the upstream vacuum between the valve and the orifice plate at amaximum of about 10 inches of water. The orifice in plate 30 is thensized so that in the normal range of flow the pressure drop therethroughwill result in a maximum vacuum of about four to 5 inches of water inthe engine crankcase under normal blowby flow conditions.

In operation, vacuum created in the turbocharger air inlet by thedrawing of inlet air through the air filters causes a pressuredifferential that establishes a flow of crankcase vapors through theventilation system and into the turbocharger air inlet. When inletvacuum is low, as at engine idle, regulating valve 32 remains fullyopen, permitting free flow of vapors therethrough and the pressure dropthrough orifice plate 30 is small.

As engine speed and load are increased, the vacuum between the valve 32and orifice plate 30 increases until the predetermined control pressureis reached, after which the valve closes as necessary to limit themaximum vacuum between the valve and orifice plate to the desiredcontrol pressure (e.g. 10 inches of water) no matter how high the vacuumin the turbocharger air inlet becomes. Pressure drop through the orificeplate 30 remains relatively low (maximum of about 5 inches of water)under blowby conditions encountered during normal operation, since theorifice is sized not to greatly restrict normal vapor flow.

However, in the case of abnormal engine operation, such as might becaused by a cracked piston or a scored liner allowing excessive blowbyto escape from the engine cylinders into the engine crankcase, theresulting increased flow will be increasingly restricted by the orificeplate 30 until a positive pressure is developed in the engine crankcase.This pressure will, at a predetermined value, actuate the crankcasepressure detector 22 which will in turn shut down the engine so that itmay be inspected to determine the cause of the faulty operation.

The limitation of the maximum downstream vacuum acting on the orificeplate through the action of the regulating valve is important sinceit-permits the use of a sufficiently large orifice to have only a smalleffect on normal blowby flows. The arrangement reduces the pressuredifferential required across the orifice to de velop a pressure in thecrankcase under abnormal high blowby conditions which thus allows theuse of a larger, less restrictive, orifice than would be possible if theturbocharger air inlet vacuum was allowed to act directly on the orificeplate.

The function of the orifice plate in the system could, if desired, beperformed by some other type of fixed resistance suitably arranged toprovide the proper restriction to flow in relation to the normal andabnormal engine operating conditions which might be encountered. Suchresistance might be provided merely by sizing the connections tothe-regulating valve to adequately restrict the passage of excessiveflow for the particular engine arrangement. Preferably, where thedevices making up the crankcase ventilating system are intended to beused on a line of engines of differing sizes and blowby characteristics,an arrangement will be utilized with provision being made for the systemto accept any one of a number of different orifice plates with varioussized orifices, depending on the engine application. In this way asingle regulating valve can be made to serve for application to any of anumber of different engines, with the system being properly balanced bythe use of an orifice sized for the particular application. Also, ifdesired, the regulating valve may be made adjustable to provide forselection of the upstream controlled pressure best suited for aparticular application. It should be apparent that numerous othervariations and changes could be made in the crankcase ventilation systemdisclosed herein without departing from the inventive concepts involved.Accordingly, it is intended that the invention be limited only by thelanguage of the following claims.

We claim: 1. The combination with an internal combustion engine having acrankcase and a combustion air inlet of engine shutdown means connectedto the engine crankcase and responsive to a predetermined positivepressure therein to stop the engine,

crankcase ventilation means communicating said crankcase with said airinlet for drawing crankcase vapors into the combustion air stream,

orifice means in said communicating means and providing a fixedrestriction to fluid flow therethrough, and

regulating valve means in said communicating means downstream of saidorifice means, said valve means providing a variable restriction tofluid flow and being operative to limit the negative control pressuresupstream thereof to a predetermined value regardless of greater negativepressures in the air inlet,

said control pressure limit being chosen and said orifice means beingsized to permit passage of a sufficient flow of crankcase vapors duringnormal engine operation to maintain a predetermined maximum vacuum inthe engine crankcase but to provide a sufficient flow restriction tocause development of positive pressure in the crankcase sufficient toactuate said shutdown means to stop the engine when there occurs anabnormally high flow of blowby into the crankcase indicative of enginemalfunction.

2. A crankcase ventilation system in combination with an internalcombustion engine having a combustion air inlet, a crankcase and engineshutdown means connected with said crankcase and adapted to be actuatedby a predetermined positive pressure therein to terminate engineoperation, said crankcase ventilation means comprising meanscommunicating said crankcase with said air inlet for drawing a flow ofcrankcase vapors into the combustion air stream,

regulating valve means in said communicating means and providing avariable restriction to fluid flow therethrough, said valve means beingresponsive to system pressures upstream thereof to vary said restrictionin a manner to maintain a predetermined maximum vacuum upstream thereof,and

fixed orifice means in said communicating means between said regulatingvalve means and said crankcase, said orifice means being sized torestrict fluid flow sufficiently to cause development of a positivepressure in the crankcase to actuate said shutdown means underpredetermined conditions of excess engine blowby but to allow thepassage of sufficient ventilation flow to permit the establishment of apredetermined maximum crankcase vacuum under normal engine operatingconditions.

3. The combination of claim 2 and further including an oil separator insaid communicating means, upstream of said orifice means, said oilseparator being adapted to separate and return to the engine crankcaseexcess oil passing into the ventilation system with the crankcasevapors.

' 4. An internal combustion engine having in combination anexhaust-driven turbocharger operable to supply varying amounts ofcombustion air to the engine under various engine operating conditions,

a combustion air inlet to the turbocharger subject to substantialvariations in sub-ambient air pressure under the varying air flows drawninto said turbocharger,

an enclosed crankcase into which engine blowby gases are received invarying amounts during engine operation,

pressure responsive means connected with said crankcase and responsiveto a predetermined, positive pressure therein to stop said engine,

crankcase ventilation means communicating said crankcase with said airinlet for drawing crankcase vapors into the combustion air stream,

a regulating valve in said communicating means and providing a variablerestriction to fluid flow therethrough, said valve being operable tovary said restriction so as to limit the vacuum immediately upstreamthereof to a predetermined maximum, and a fixed orifice in saidcommunicating means between said regulating valve and said crankcase andsized to permit a sufficient flow of crankcase vapors through saidcommunicating means to establish a substantial crankcase vacuum undernormal engine operating conditions but to restrict flow sufi'iciently tocause development of a positive pressure in the crankcase sufficient toactuate said pressure responsive means under predetermined conditions toexcess engine blowby.

1. The combination with an internal combustion engine having a crankcaseand a combustion air inlet of engine shutdown means connected to theengine crankcase and responsive to a predetermined positive pressuretherein to stop the engine, crankcase ventilation means communicatingsaid crankcase with said air inlet for drawing crankcase vapors into thecombustion air stream, orifice means in said communicating means andproviding a fixed restriction to fluid flow therethrough, and regulatingvalve means in said communicating means downstream of said orificemeans, said valve means providing a variable restriction to fluid flowand being operative to limit the negative control pressures Upstreamthereof to a predetermined value regardless of greater negativepressures in the air inlet, said control pressure limit being chosen andsaid orifice means being sized to permit passage of a sufficient flow ofcrankcase vapors during normal engine operation to maintain apredetermined maximum vacuum in the engine crankcase but to provide asufficient flow restriction to cause development of positive pressure inthe crankcase sufficient to actuate said shutdown means to stop theengine when there occurs an abnormally high flow of blowby into thecrankcase indicative of engine malfunction.
 2. A crankcase ventilationsystem in combination with an internal combustion engine having acombustion air inlet, a crankcase and engine shutdown means connectedwith said crankcase and adapted to be actuated by a predeterminedpositive pressure therein to terminate engine operation, said crankcaseventilation means comprising means communicating said crankcase withsaid air inlet for drawing a flow of crankcase vapors into thecombustion air stream, regulating valve means in said communicatingmeans and providing a variable restriction to fluid flow therethrough,said valve means being responsive to system pressures upstream thereofto vary said restriction in a manner to maintain a predetermined maximumvacuum upstream thereof, and fixed orifice means in said communicatingmeans between said regulating valve means and said crankcase, saidorifice means being sized to restrict fluid flow sufficiently to causedevelopment of a positive pressure in the crankcase to actuate saidshutdown means under predetermined conditions of excess engine blowbybut to allow the passage of sufficient ventilation flow to permit theestablishment of a predetermined maximum crankcase vacuum under normalengine operating conditions.
 3. The combination of claim 2 and furtherincluding an oil separator in said communicating means, upstream of saidorifice means, said oil separator being adapted to separate and returnto the engine crankcase excess oil passing into the ventilation systemwith the crankcase vapors.
 4. An internal combustion engine having incombination an exhaust-driven turbocharger operable to supply varyingamounts of combustion air to the engine under various engine operatingconditions, a combustion air inlet to the turbocharger subject tosubstantial variations in sub-ambient air pressure under the varying airflows drawn into said turbocharger, an enclosed crankcase into whichengine blowby gases are received in varying amounts during engineoperation, pressure responsive means connected with said crankcase andresponsive to a predetermined, positive pressure therein to stop saidengine, crankcase ventilation means communicating said crankcase withsaid air inlet for drawing crankcase vapors into the combustion airstream, a regulating valve in said communicating means and providing avariable restriction to fluid flow therethrough, said valve beingoperable to vary said restriction so as to limit the vacuum immediatelyupstream thereof to a predetermined maximum, and a fixed orifice in saidcommunicating means between said regulating valve and said crankcase andsized to permit a sufficient flow of crankcase vapors through saidcommunicating means to establish a substantial crankcase vacuum undernormal engine operating conditions but to restrict flow sufficiently tocause development of a positive pressure in the crankcase sufficient toactuate said pressure responsive means under predetermined conditions toexcess engine blowby.